Document processing method and system

ABSTRACT

A method and system for expanding a document set as a search data source in the field of business related search. The present invention provides a method of expanding a seed document in a seed document set. The method includes identifying one or more entity words of the seed document; identifying one or more topic words identifying one or more topic words related to the based entity word in the seed document where the entity word is located; forming an entity word-topic word pair from each identified topic word and the entity word on the basis of which each topic word is identified; and obtaining one or more expanded documents through web by taking the entity word and topic word in the each entity word-topic word pair as key words at the same time. A system for executing the above method is also provided.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 from ChinesePatent Application No. 200910203108.X filed May 27, 2009, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a document processing technique, andmore particularly, relates to a method and system for expanding adocument set as a search data source in the enterprise search field.

2. Description of the Related Art

Today's enterprises have increasing types of electronic documents anddata information. How to utilize such information to help anenterprise's business development and strategy decisions has attractedgreat attention. Enterprise search technology provides an effective wayto help enterprises process such ever increasing data information.However, not all data are suitable as a search data source in anenterprise search.

The traditional information source upon which the search of a generalsearch engine is based is a mass information source. The search resultis also mass data information. A great number of search results may notbe desired by a user, and the enterprise search user can seldom obtainthe desired information by eliminating noise from such mass datainformation. Thus, in the enterprise search field, for a particularbusiness demand such as performing market analysis on an industry ordetermining an enterprise for investment, it is impossible to collectall the Web data for performing a search due to limitation of resources.However, as much relevant information as possible must be acquired.

With the expeditious increase of Internet based documents, the datasource for an enterprise search must be constantly updated and extended.Thus, a significant challenge in the field of enterprise searchtechnology is to effectively and automatically extend the search datasource for enterprise search services to help an enterprise collectinformation useful to businesses from a mass of web data. This will helpeliminate unnecessary “noisy” information to promote data source utilityand save storage resources for the search data source.

In the related art, a user of an enterprise search service recommendsrelatively valuable documents which he or she obtained from anenterprise search service system. The documents were stored in aninformation memory device of the enterprise search service system andthen became a public enterprise search data source. Further, a systemadministrator for the enterprise search service keeps a close eye on thechange of web information at any moment and adds useful information tothe enterprise search data source. However, the above manners ofexpanding search data source can not automatically implement expansionbased on the existing documents in the data source for enterprisesearch, which is totally dependent on actions of users of the enterprisesearch service and the system administrator. This not only consumes timeand energy but also has low efficiency in expanding the data source.

SUMMARY OF THE INVENTION

It is desired to provide a technical solution capable of automaticallyexpanding documents without requiring a considerable amount of manualwork while maintaining the precision and accuracy of document expansion.

According to an aspect of the present invention, there is provided adocument processing method. The method includes:

identifying, based on each identified entity word, one or more topicwords related to the based entity word in the seed document where theentity word is located;

forming an entity word-topic word pair from each identified topic wordand the entity word as the basis for identifying the each identifiedtopic word; and obtaining one or more expanded documents through the webby taking the entity word and topic word in each entity word-topic wordpair as key words at the same time, wherein the expanded documentsinclude not only the entity word in the each entity word-topic word pairbut also the topic word in the each entity word-topic word pair.

According to another aspect of the present invention, there is provideda document processing method, which includes:

receiving one or more entity word-topic word pairs;

identifying one or more entity words of the candidate document, whereinthe entity words are words indicating focused entities of the candidatedocument;

identifying, based on each identified entity word, one or more topicwords related to the based entity words in the candidate document wherethe entity word is located;

determining whether to add the candidate document into a filtereddocument set using the entity words and topic words in the given entityword-topic word pairs and the identified entity words and topic words inthe candidate document; and

adding the candidate document into a filtered document set in responseto determining that the candidate document should be added into thefiltered document set, wherein:

-   -   each of the given entity word-topic word pairs include an entity        word and a topic word;    -   all entity words in the entity word-topic word pair form an        entity word set; and        all topic words in the entity word-topic word pair where each        entity word is located form a topic word set corresponding to        the entity word.

According to a yet aspect of the present invention, there is provided asystem for expanding a seed document in a seed document set. The seeddocument set includes at least one seed document and the systemincludes:

entity word identifying means for identifying one or more entity wordsof the seed document, the entity words being words indicating focusedentities of the seed document;

topic word identifying means for identifying, based on each identifiedentity word, one or more topic words related to the based entity word inthe seed document where the entity word is located;

pairing means for forming an entity word-topic word pair from eachidentified topic word and the entity word based on which the each topicword is identified; and

document expanding means for obtaining one or more expanded documentsthrough the web by taking the entity word and topic word in the eachentity word-topic word pair as key words at the same time, the expandeddocuments including not only the entity word in each entity word-topicword pair but also the topic word in the each entity word-topic wordpair.

According to still another aspect of the present invention, there isprovided a a system for filtering a candidate document in a candidatedocument set. The candidate document set includes at least one candidatedocument. The system includes:

document processing system, including: receiving means for receiving oneor more entity word-topic word pairs;

entity word identifying means for identifying one or more entity wordsof the candidate document, the entity words being words indicatingfocused entities of the document;

topic word identifying means for identifying based on the identifiedeach entity word, one or more topic words related to the based entityword in the candidate document where the entity word is located; and

determining means for determining whether to add the candidate documentinto a filtered document set using the entity words and topic words inthe given entity word-topic word pairs and the identified entity wordsand topic words in the candidate document, and in response to adetermining result yes, adding the candidate document into a filtereddocument set wherein:

-   -   each of the given entity word-topic word pairs include an entity        word and a topic word;    -   all entities in the entity word-topic word pair form an entity        word set; and    -   all topic words in the entity word-topic word pair where each        entity word is located forming a topic word set corresponding to        the entity word.

According to the methods and systems of the present invention, expandingor filtering the existing documents can be performed automatically,without consuming a considerable amount of manual work. Moreover, suchexpanding or filtering is based on performing entity word-topic wordanalysis to existing documents, which improves the basis nature andaccurateness of document expansion or filtering.

Different from a traditional search engine which is dependent on dataexpansion performed by super links between web pages, the focusedinformation of an enterprise generally has specific entities andrelevant topics. Thus, the technical solution as proposed here mainlyuses the focused entities in an article's content and the analysis onthe topics to further explore the enterprise user's demand oninformation, thereby performing automatic expansion of documents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow chart of a document processing method according tothe present invention;

FIG. 2 shows a flow chart of a method of identifying entity words in adocument with focused named entity recognition technology FNER;

FIG. 3 shows a flow chart of a method of identifying topic words in adocument with focused topic detection technology FTD;

FIG. 4 shows an architecture diagram of a general search engine-basedweb crawler according to an embodiment of the present invention;

FIGS. 5A-5G are diagrams of each procedure of the process of performingentity word and topic word identification on a Chinese document;

FIGS. 6A-6F are diagrams of each procedure of the process of performingentity word and topic word identification on an English document;

FIG. 7 shows a flow chart on the basis of the document processing methodas shown in FIG. 1 and comprising steps of filtering the processeddocument;

FIG. 7A shows a flow chart of a document processing method for filteringa given candidate document set with a given entity word-topic word pair;

FIG. 8 shows a flow chart of a method of filtering an expanded documentset according to an embodiment of the present invention;

FIG. 8A shows a detailed flow chart according to filtering steps in theflow chart shown in FIG. 7A;

FIG. 9 shows a structural diagram of a document processing systemaccording to the document processing method as shown in FIG. 1;

FIG. 10 shows a structural diagram of a document processing systemaccording to the document processing methods as shown in FIG. 7 and FIG.8;

FIG. 11 shows a structural diagram of a document processing systemaccording to the document processing methods as shown in FIG. 7A andFIG. 8A; and

FIG. 12 shows a structural diagram of an implementation of an enterprisesearch service system according to a method of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings.

FIG. 1 shows a flow chart of a document processing method according tothe present invention. The method starts at step 101. Operations of thesteps 101-104 are performed on each seed document in a seed documentset. At the step 101, entity words of the seed document are identified.A seed document set is a document set comprising at least one seeddocument, and the seed document refers to a document that is determinedto be subject to an expansion operation. In other words, all documentscomprised in a seed document set must be subject to the operations ofthe steps 101-104. The seed documents in a seed document set may bephysically stored in the same memory device or in different memorydevices. Even though a certain document and a seed document arephysically stored in the same memory device or are obtained in a commonmanner such as by recommended by users of an enterprise search service,if it is not required to perform the expansion operations as shown inthe steps 101-104 on the certain document, the certain document can notbe regarded as a seed document and thus is not included in the seeddocument set.

A seed document comprised in a seed document set may be recommended byusers of an enterprise search service. After a user reads a documentwhich he thinks is valuable locally or from a remote server through theweb, he or she may recommend the document to the enterprise searchserver. The document is thereby saved in the seed document set. Thoseskilled in the art may appreciate that the user recommendation is onlyone way of generating a seed document set, and the other ways may beadopted to generate a seed document set, for example importedautomatically from other database.

An entity word is a word contained in a document and refers to one ormore focused named entities in an article. For each article, one or moreentity words can be identified. Entity words in a document may beidentified with the focused named entity recognition technology (FNER),and the method for using the FNER technology to identify entity wordswill be specifically shown and explained accordingly in FIG. 2. Inresponse to the entity words identified in the seed document at step101, the topic words of the seed document are identified at step 102based on the identified entity words.

The topic words are words different from the entity words, whichindicate important topics associated with the identified entity words inan article and have a certain part of speech, in most cases a noun orverb. Like the entity words, the topic words are also words in adocument. It should be emphasized that a topic word is associated withan entity word. A topic word must be identified based on an entity wordidentified from a document. Though a variety of parameters need to beintroduced in the process of identifying topic words, the associationsof other words than the entity words identified in an article with theentity words are significant and indispensible parameters in the processof identifying the topic words.

The topic words in a document may be identified through a focused topicdetection technology (FTD). The method of using the FTD technology toidentify topic words will be shown and explained accordingly in FIG. 3.

Those skilled in the art may appreciate how parameters associated withentity words are introduced during the process of identifying topicwords from the FTD flow chart as shown in FIG. 3 and the correspondingliteral description, so as to embody the correlation between theidentified topic words and entity words. It should be further pointedout that one or more topic words may be identified based on a sameidentified entity word, because in a document, there may be a pluralityof topic words associated with an entity word of the document. It shouldbe further emphasized that the topic words correspond to the entitywords. Specifically, a plurality of entity words may be identified for asame document, and then topic words are identified in the document basedon each identified entity word, respectively.

Through the steps 101 and 102, the entity words and topic words in eachdocument in a seed document set have been identified. At the step 103,each topic word as identified and the entity word as the basis foridentifying each topic word form an entity word-topic word pair. Inparticular, the manner of forming an entity word-topic word pair at step103 should be noted. Since a seed document set may comprise a pluralityof documents and each document may further comprise a plurality ofentity words and a plurality of topic words to be identified, it is notthe case that all identified entity words and topic words in a documentin a seed document set form pairs randomly, but that each identifiedtopic word and the entity word as the basis for identifying the topicword form an entity word-topic word pair. An example is shown in table A(document 1, document 2 and document 3 are all seed documents in a seeddocument set):

TABLE A Document No. Document 1 Document 2 Document 3 Entity Words A1 A2A3 A4 A5 A1 Topic Words B1 B1 B2 B3 B4 B5 B2 B5

From Table A, it is seen that the three entity words as identified indocument 1 at step 101 are: A1, A2, and A3, respectively. Based on theentity word A1, the topic word B1 corresponding to A1 is identified atstep 102, the topic word B1 corresponding to A2 is identified at step102; and based on the entity word A3, two topic words B2 and B3corresponding to A3 are identified at step 102, respectively. Likewise,the entity words and topic words of document 2 and document 3 are alsoidentified. Then, the entity word-topic word pairs that can be formed bythe above identified entity words and topic words at step 103 are thefollowing 8 pairs: A1-B1, A2-B1, A3-B2, A3-B3, A4-B4, A5-B5, A1-B2, andA1-B5. However, an entity word-topic word pair such as A4-B5 can not beformed, because B5 is identified based on the entity word A5, not basedon the entity word A4.

From Table A, it can also be seen that a plurality of entity words maybe identified in a same document (for example A4 and B5 identified indocument 2), a plurality of topic words may be identified based on asame entity word (for example, two topic words B2 and B5 identified indocument 3 based on the entity word A1), and a same entity word can beidentified in different documents (for example the entity word A1 can beidentified both in document 3 and document 1).

At the step 104, taking the entity word and topic word in each formedentity word-topic word pair as key words at the same time, one or moreexpanded documents are obtained through web search. An expanded documentset comprising one or more expanded documents is thereby generated fromthe seed document set. With A1-B1 which can form an entity word-topicword pair in table 1 as an example, a new document is searched anddownloaded through the web with A1-B1 as key words (during the searchprocess, A1 and B1 have a relationship “and”, not “or”), and thedownloaded new document not only comprises A1 but also comprises B1.Thus the downloaded new document forms an expanded document set.

It should be noted that various manners can be adopted to implement theprocess of automatically searching and downloading new documents throughweb. For example new documents can be downloaded through the web crawlertechnology-based general search engine architecture. FIG. 4 shows adiagram of the architecture of a general search engine-based webcrawler.

To sum up, through the steps 101-104 in FIG. 1, a seed document set canbe expanded as a seed document set plus expanded document set, therebyachieving a technical effect of automatically expanding the originalsearch data source document in the enterprise search service field.

FIG. 2 shows a flow chart of a method of identifying entity words in adocument with a FNER technology. For a given document, the automaticsegmentation processing is performed at step 201, that is, segmentingthe words comprised in a document one by one. Methods such as themaximum match method (MM method), the reverse maximum match method (OMMmethod), the word-by-word traversing match method, and the segmentationmark establishment method can be used for performing the automaticsegmentation processing.

After the automatic segmentation processing ends, the automatic POStagging is performed at step 202, the POS indicating the part of speechof a word, such as noun, verb, preposition, or adjective. The automaticPOS tagging can automatically tag POS to the words in a document througha computer based on probability statistics and based on a rule. Inparticular, common methods such as CLAWS and VOLSUNGA in the art can beused for the automatic POS tagging. The automatic POS tagging processingmay result in tagging a noun as n, tagging a verb as v, tagging anadjective as a, and tagging a number as m.

At step 203, candidate entity words are identified. It should beemphasized that an entity word refers to a word representing a name of aperson, a name of an address, or a name of an organization. An entityword must be a noun, that is, it is the word tagged as noun (n) at step202. The technology for identifying candidate entity words is mainly toextract features of each word in an article, for example, a precedingword and a following word, respective part of speech of the precedingand following words, and whether the word appears in a semanticdictionary such as the name of a person, name of an address, and prefixand affix of the name of an organization.

Then, the classification determination is performed based on astatistical model of entity identification, such that a word exceeding athreshold is determined as a candidate entity word. In this way, theentity words are distinguished from normal nouns. On the basis ofobtaining the candidate entity words, a series of features are extractedfrom each candidate entity word at step 204, where the feature values ofa series of features extracted from each candidate entity word form afeature vector. For example, e is a candidate entity word identified ina document, and if m number of features are extracted with regard to theentity word, the feature vector of the candidate entity word e can beexpressed as X={x₁, x₂, . . . , x_(m)}. The extracted features about thecandidate entity word may be a frequency of the candidate entity wordappearing in an article, whether the candidate entity word appears inthe title, whether its left neighboring and right neighboring words areother candidate entity words, and the distribution of the candidateentity word in the document, etc.

At step 205, a threshold is set and a weight for each feature value inthe feature vector is set. It should be pointed out that the thresholdand the weight for each feature value are typically set at step 205 in amachine learning manner. Generally speaking, the process of machinelearning algorithm is as follows: first, preparing some manually taggedtraining sample sets such as each class includes a certain number ofexamples belonging to this class; extracting features according to aspecific method, wherein due to difference in classification scenariosand data, the classification features extracted are also different fromone another; and finally, the machine learning algorithm reads featuresof each training sample, and derives a classification model, that is,the weight of each feature, or the contribution degree of the feature tothe classification, through certain learning criteria. For example, thespatial partition distance between a positive sample and a negativesample is the maximum, or the classification error is minimum. Then thetraining process ends.

Like the training process, during the online classification, featuresare extracted from a sample with an unknown class. Then, the similaritydegree of the sample to each class is computed based on theclassification model derived in the training process, and the finalclassification is determined based on a preset threshold. The currentlywidely applied machine learning algorithms are as follows; Naïve-Bayesalgorithm, Decision Tree algorithm, and Support Vector Machinesalgorithm, wherein the Support Vector Machines algorithm is currently awell-known best classification algorithm which can achieve the bestclassification precision rate.

At step 206, the following formula is used to calculate the score (x) ofeach candidate entity word:

${{score}\mspace{14mu}(x)} = {b + {\sum\limits_{j = 1}^{m}\left( {w_{j}*x_{j}} \right)}}$wherein b represents the threshold set at step 205, w_(j) represents theweight of the feature x_(j), w_(j) can be a positive value or a negativevalue; when w_(j) is a negative value, it indicates that it has anegative effect for selecting the candidate entity words with a featurex_(j) as entity words. After calculating the score of the candidateentity word according to the above formula at step 206, the scorederived at step 207 is compared with the threshold set at step 205, andif the value of the score (x) is greater than 0, the candidate entityword is identified as an entity word, and if the value of the score (x)is smaller than 0, then the candidate entity word is not identified asan entity word. Until now, the same processing and determination isperformed on each candidate entity word identified at step 203, so as toidentify the entity words in the document.

FIG. 3 shows a flow chart of a method for identifying topic words in adocument based on the identified entity words using the focused topicdetection (FTD) technology. At step 301, the document whose entity wordshave been identified is subject to the automatic segmentation andautomatic POS tagging processing. It should be noted that in order toshow schematically a complete FTD flow, step 301 is added in FIG. 3. Infact, step 301 has been implemented in the FNER flow as shown in FIG. 2,thus it is unnecessary for reimplementation in the FTD flow, and thus itis completely feasible to directly use the processing result ofautomatic segmentation and automatic POS tagging in the FNER flow.

At step 302, the stop words, the entity words and the candidate entitywords in the document are filtered. Here, the entity words to befiltered are those entity words identified in the FNER flow as shown inFIG. 2, while the stop words refer to those words that can not be topicwords, for example: adjectives such as beautiful or excellent andadverbs such as “of”. Preferably, the topic words are nouns. Lesspreferably, topic words may also be verbs. The result of automatic POStagging may be used to implement filtering at step 302.

At step 303, a distance between each residual word and an entity word ina filtered document is calculated. The residual words refer to the wordsleft in the document after filtering. The distance between a residualword and an entity word refers to the number of words spaced between theresidual word and the entity word, and here, during calculating thenumber of words spaced, the entity words, the candidate entity words andthe stop words that have been filtered shall be counted. The basis forsuch practice is that, generally, the average distance between a topicword and an entity word is smaller than the average distance between anon-topic word and an entity word. At step 304, the frequency of eachresidual word and an entity word appearing in a same sentence in afiltered document is calculated.

Those skilled in the art may appreciate that step 303 and step 304embody that topic words are correlated with entity words, that is, thetopic words are identified based on specific, identified entity words.It should be particularly pointed out that step 303 and step 304 areonly two exemplary parameters embodying the relationship between topicwords and entity words, and parameters capable of embodying therelationships between the topic words and entity words may further havea plurality of kinds, such as, the frequency of an entity word and atopic word appearing in a same paragraph at the same time, the frequencyof an entity word and a topic word appearing in a designated distancerange, the frequency of an entity word and a topic word appearing in asubtitle and the content affiliated to the subtitle in a document at thesame time.

The so-called “frequency of an entity word and a topic word appearingwithin a designated distance range” refers to the times a topic wordappears within a specific distance, for example 3 words, spaced from anentity word. If a word appears within 3 words spaced from the identifiedtopic word, whether it is two words or one word, the feature value canobtain the same weight and score, with no further distinguishing withina specific distance. The so-called “frequency of an entity word and atopic word appearing in a subtitle and the content affiliated to thesubtitle in a document at the same time” refers to a situation in whichin some web document, besides a main title, there are a plurality ofsubtitles, and each subtitle is attached with a segment of contentregarding the subtitle. Thus the frequency of an entity word and a topicword appearing in the subtitle and the content affiliated to thesubtitle in a document at the same time can also embody the relationshipbetween the entity word and the topic word.

To sum up, the relationship between entity words and topic words can beembodied by a plurality of parameters (feature values), to therebyembody the “dependency relationship” of topic words based on theidentified entity words. Besides the above enumerated plurality ofparameters, excluding the feature values, any parameter employed bythose skilled in the art, as long as it can embody the relationshipbetween entity words and topic words, that is, identifying topic wordsbased on the identified entity words, falls into the protection scope ofthe present invention.

At step 305, feature values of each residual word are extracted to forma feature vector thereof. The features extracted at step 305 comprisethe distance and frequency derived at step 303 and step 304, as well asother features of the residual word irrelevant to the entity word, forexample, frequency of residual words appearing in the document, lengthsof residual words, and the number of documents including the residualwords in a document set having the same identified entity words.

At step 306, a threshold for identifying the topic word is set, and aweight value for each feature in the feature vector is set. Like at step205 of setting a threshold for identifying entity words and setting aweight for each feature value in the feature vector, at step 306, athreshold for identifying topic words and a weight value for eachfeature in the feature vector are also set in a machine learning manner.At step 307, for each residual word, a score is calculated based on theset weight value and feature vector Y={y₁, y₂, . . . , y_(m)}. Thecalculation formula is:

${{score}\mspace{14mu}(y)} = {c + {\sum\limits_{j = 1}^{m}\left( {w_{j}*y_{j}} \right)}}$wherein c represents the threshold as set at step 306, w_(j) representsthe weight of the feature y_(j), w_(j) can be a positive value or anegative value; when w_(j) is a negative value, it indicates that it hasa negative effect for selecting the residual words with a feature y_(j)as topic words. After calculating the score of the residual wordaccording to the above formula at step 307, the score derived at step308 is compared with the threshold set at step 306, and if the value ofthe score (y) is greater than 0, the residual word is identified as atopic word, and if the value of the score (y) is smaller than 0, thenthe residual word is not identified as a topic word. By far, eachresidual word is subject to the same processing and determining, withthe topic words in the document corresponding to the previouslyidentified entity words being filtered out and identified.

Hereinafter, an instance for identifying entity words in a specificChinese document and for identifying topic words based on the identifiedentity words is described:

1. Using FNER Technology to Realize Identification of Entity Words

Step 1 Automatic Segmentation and Automatic POS Tagging

Assume a given Chinese document is shown in FIG. 5A. The effect aftersegmenting the document with a program is shown in FIG. 5B, and theeffect after automatic POS tagging with a program is shown in FIG. 5C,wherein /n indicates a noun, /v indicates a verb, /a indicates anadjective, /m indicates a number.

Step 2 Identifying Candidate Entity Words

As shown in FIG. 5D, the extracted candidate entity words include acompany name “

(JIANHUA)” which is determined based on the neighboring “

(digital)” and “

(company)”, an address name determined from the neighboring “

(Nan Qian)” and a person name “

(Zhang San)” determined from the neighboring “

(manager).” These candidate entities are expressed in bold lines in FIG.5D.

Step 3

For each candidate entity word, a series of features are extracted. Forexample, a frequency of the candidate entity word appearing in thearticle, whether it appears in the title, whether its left neighboringand right neighboring words are candidate entity words, and thedistribution of the candidate entity word in the article.

For example the statistics on the features only considering frequencyinformation is as follows:

(JIANHUA): once in the title, 4 times in the text

(Zhongshan): once in the text

(Zhang San): once in the text

Step 4

Based on the candidate entity words as identified in step 3, FNERclassification model, derived through the machine learning, is appliedto the feature vector X={x₁, x₂, . . . , x_(m)} for each candidateentity word, thereby obtaining an estimate score (probability). If theestimate score is greater than the set threshold, the candidate entityword is determined as an entity word.

The following formula is used to calculate the score (x) of eachcandidate entity word:

${{score}\mspace{14mu}(x)} = {b + {\sum\limits_{j = 1}^{m}\left( {w_{j}*x_{j}} \right)}}$

The table in FIG. 5E shows the process and result of calculating entitywords with the above formula, wherein the threshold value 0.5 in thetable of FIG. 5E corresponds to the inverse number of b in the formula,that is, −b. Thus, the entity word obtained in the above example is:

(JIANHUA).

2. Specific Process of Identifying Topic Words Based on the IdentifiedEntity Word “

(JIANHUA)”.

Step 1

It is necessary to segment and POS tag the document based on eachidentified entity word. The document after automatic segmentation andautomatic POS tag processing is shown in FIG. 5C. It should be notedthat since the automatic segmentation processing and POS tag processinghave been performed during identifying entity words, it is generallyunnecessary to re-perform the automatic segmentation and POS taggingprocessing in identifying topic words.

Step 2

Selecting a focused POS class (typically a noun) and filtering out thestop words (for example

(of), full stop (∘), comma (,)) and the identified entity words in adocument. The result of the above document subject to filter processingis shown in FIG. 5F (the slanted and underlined words are the filteredentity words). It should be noted that two candidate entity words “

(Zhang San)” and “

(Zhongshan)” have been filtered out and thus are not shown in FIG. 5F. “

(JIANHUA)”, in fact, has been filtered out. However, since theidentified entity word “

(JIANHUA)” has to be based on when identifying topic words, “

(JIANHUA)” is shown slantingly and underlined in FIG. 5F.

Step 3

The FTD technology (derived through computer learning) is employed byconsidering parameters such as the distance of the residual words (i.e.the words left after all candidate entity words have been filtered outfrom the document) spaced away from the identified entity words, afrequency of the residual words and identified entity words appearing inthe same sentence, and the times of the residual words appearing in thedocument, with the topic words being outputted.

For example, words with relatively high appearing frequency in theChinese document are:

(Digital) once in the title, 6 times in the text

(Company) 3 times in the text

(Industry) once in the title, once in the text

(Technology) twice in the text

For each residual word, a score is calculated based on the set weightvalue and feature vector Y={y₁, y₂, . . . , y_(m)}. The calculationformula is:

${{score}\mspace{14mu}(y)} = {c + {\sum\limits_{j = 1}^{m}\left( {w_{j}*y_{j}} \right)}}$

The table in FIG. 5G shows the process and result of calculating topicwords with the above formula, wherein the threshold value 0.5 in thetable of FIG. 5G corresponds to the inverse number of c in the formula,that is, −c. Thus, the topic word obtained in the above example is:

(Digital). Then, the entity word-topic word pair is “

(JIANHUA)-

(Digital)”.

Note: words like “

(month)”, “

(date)”, and “

(year)” in document 1 are typically ranked with a lower score due to atoo short length; the meaning expressed by a short word is typicallyvery limited.

Hereinafter, an instance for identifying entity words in a specificEnglish document and for identifying topic words based on the identifiedentity words is described:

1. Using FNER Technology to Realize Identification of Entity Words

Step 1 Automatic POS Tagging

Assume a given English document is shown in FIG. 6A. The effect afterautomatic POS tagging with a program is shown in FIG. 6B, wherein /nindicates a noun, /v indicates a verb, /a indicates an adjective, and /mindicates a number. It should be noted that for an English document,automatic segmentation is unnecessary.

Step 2 Identifying Candidate Entity Words

As shown in FIG. 6C, the extracted candidate entity words include acompany name “JIANHUA” determined by the neighboring TV, address names“Beijing” and “China” determined through the neighboring “in”, and “of”,which candidate entity words are shown in bold lines in FIG. 6C.

Step 3

For each candidate entity word, a series of features are extracted, forexample: the frequency of the candidate entity word appearing in thearticle, whether the word appears in the title, whether the word's leftneighboring and right neighboring words are candidate entity words, andthe distribution of the candidate entity word in the article.

For example, the statistics on the features only considering frequencyinformation is as follows:

JIANHUA: once in the title, twice in the text

China: twice in the text

Beijing: once in the text

Step 4

Based on the candidate entity words as identified in step 3, FNERclassification model, derived through machine learning, is applied tothe feature vector X={x₁, x₂, . . . , x_(m)} for each candidate entityword, thereby obtaining an estimate score (probability), and if theestimate score is greater than the set threshold, the candidate entityword is determined as a entity word.

The following formula is used to calculate the score (x) of eachcandidate entity word:

${{score}\mspace{14mu}(x)} = {b + {\sum\limits_{j = 1}^{m}\left( {w_{j}*x_{j}} \right)}}$

The table in FIG. 6D shows the process and result of calculating entitywords with the above formula, wherein the threshold value 0.5 in thetable of FIG. 6D corresponds to the inverse number of b in the formula,that is, −b. Thus, the entity word obtained in the above example is:JIANHUA.

2. Specific Process of Identifying Topic Words Based on the IdentifiedEntity Word “JIANHUA”.

Step 1

It is necessary to POS tag the document based on each identified entityword while unnecessary for automatic segmentation. The document afterPOS tagging processing is shown in FIG. 6B. It should be noted thatsince the POS tagging processing has been performed during identifyingentity words, it is generally unnecessary to re-perform the POS taggingprocessing in identifying topic words.

Step 2

Selecting a focused POS class (typically a noun) and filtering out thestop words (for example “of”) and candidate entity words in a document.The result of the above document subject to filter processing is shownin FIG. 6E (the slanted and underlined words are the filtered entitywords). It should be noted that two candidate entity words “China” and“Beijing” have been filtered out and are thus not shown in FIG. 6E.“JIANHUA”, in fact, has been filtered out. However, since the entityword “JIANHUA” has to be based on when identifying topic words,“JIANHUA” is shown slantingly and underlined in FIG. 6E.

Step 3

FTD technology, derived through computer learning, is employed byconsidering parameters such as the distance of the residual words (i.e.the words left after all candidate entity words have been filtered outfrom the document) spaced away from the identified entity words, afrequency of the residual words and identified entity words appearing inthe same sentence, and the times of the residual words appearing in thedocument, with the topic words being outputted.

For example, words with relatively high appearance frequency in theEnglish document are:

Home: once in the title, thrice in the text

Appliance: once in the title, thrice in the text

TV: once in the title, twice in the text

Outlet: once in the title, once in the text

Exhibition: once in the text

For each residual word, a score is calculated based on the set weightvalue and feature vector Y={y₁, y₂, . . . , y_(m)}. The calculationformula is:

${{score}\mspace{14mu}(y)} = {c + {\sum\limits_{j = 1}^{m}\left( {w_{j}*y_{j}} \right)}}$

The table in FIG. 6F shows the process and result of calculating topicwords with the above formula, wherein the threshold value 0.5 in thetable of FIG. 6F corresponds to the inverse number of c in the formula,i.e. −c. Thus, the topic word obtained in the above example is: TV.Then, the entity word-topic word pair as identified in the Englishdocument is “JIANHUA-TV”.

Through the above instances of identifying entity words from a Chinesedocument and an English document and identifying topic words based onthe entity words, it is seen that regardless of the language of adocument, it can be subject to operations of identifying entity wordsand topic words through the method and system of the present invention.

FIG. 7 shows a flow chart on the basis of the document processing methodas shown in FIG. 1 and including steps of filtering a processeddocument. FIG. 7 differs from FIG. 1 in the additions of step 701 andstep 706. At step 701, a seed document recommended from an enterprisesearch service user is received to generate a seed document set. In anenterprise search service environment, the user, when obtaining adocument which he thinks valuable and possibly helpful to the search ofother user, may recommend the document to the data source storage centerof an enterprise search service, which becomes a seed document. All seeddocuments recommended by users can form a seed document set. Thepreferred manner of executing a recommendation operation may be that theuser imports the document which he thinks valuable and publishes thedocument in the search data source (seed document set) of the enterprisesearch system by clicking on the “recommend” button in the enterprisesearch system.

Steps 702-705 correspond to steps 101-104 in FIG. 1, respectively, andthe detailed contents in the four steps have been introduced previouslyand will not be detailed here. Next, the expanded document set obtainedby expansion is filtered at step 706, which corresponds to slim theexpanded document set by deleting some inexpensive documents. The reasonfor such practice is to download all documents including key words forweb search, such as entity word-topic word pairs, to form an expandeddocument set.

However, though many such new documents comprise these key words likeentity word-topic word pairs, the focused entities and topics of thedocument per se are far different from the focused entities and topicsof the enterprise search service user. In other words, the expandeddocument set formed only through the step 705 would comprise many“noises” (valueless documents or not focused documents of the user),since the search result precision of a general Internet search engineper se is limited.

A general search engine is a search based on key words. Thus, though thereturned search result comprises the key words in search, they are notnecessarily the topics of the article. Thus, it is required to searchand download the key words of the new documents, that is, entityword-topic word pairs from the web, and then the expanded document setis filtered by use of the key words to form a filtered document set, soas to filter out the “noises” in the expanded document set, therebyimproving the precision and accuracy of the seed document set. It shouldbe understood that the step 706 of filtering the expanded document setis not obligatory, because whether to remove “noises” possibly includedin the expanded document set may be determined based on differentdemands on document expansion precision. Through the method shown inFIG. 7, the new documents can be automatically downloaded from the webto thereby expanding the documents, and the downloaded new documents maybe filtered to guarantee the precision and accurateness of documentexpansion, which will not excessively consume storage resources.

It should be noted that, though in FIG. 7, the step of filteringdocuments is performed to the documents in the expanded document setwhich is generated at step 104 in FIG. 1, and the entity word-topic wordpair used for filtering is the entity word-topic word pair generated atstep 103 as shown in FIG. 1, those skilled in the art may appreciatethat the object for “filter” may be any document. A document set with abig scope may be artificially given, for example it is limited that alldocuments stored in a memory device are documents required for filter.Alternatively, mass documents may be obtained with a certain limitationcondition such as key words or without any limiting condition through anetwork such as Internet, Ethernet, local area network inside anenterprise, metropolitan area network, or radio communication network. Adocument set including these documents may act as a set of candidatedocuments to be filtered. Alternatively, users of enterprise search mayrecommend too many documents to the enterprise search system. In orderto remove some less valuable recommended documents, the expansion is notperformed to these recommended documents like the process as shown inFIG. 7, but these recommended documents are filtered by given entityword-topic word pairs.

It should be emphasized that a candidate document set is a document setcomprising one or more candidate documents, wherein each candidatedocument is required for filter operation. As a preferred embodiment,such candidate document set may be an expanded document set generated atstep 104 in accordance with the steps as shown in FIG. 1. In otherwords, a part or all of the expanded documents in the expanded documentset are candidate documents required for filter. Alternatively, thecandidate document set as shown in FIG. 7A is a subset of the expandeddocument set as shown in FIG. 1, or the candidate document set and theexpanded document set have intersection.

If a document is not required for filter, then the document would not bea candidate document and thus is not comprised in the candidate documentset, independent of whether the document is in the expanded document setgenerated at step 104 as shown in FIG. 1, or the document be physicallystored in a same memory device with other candidate documents or they beobtained in a same manner. Steps 701-705 as shown in FIG. 7 are notnecessary steps, because the “entity word-topic word pair” as a filterbasis may be a given entity word-topic word pair in various manners (forexample, given by manual input, given remotely through a network, orgiven by selecting key words from any document with certain criteria),but not the entity word-topic word pair formed by identifying entitywords and topic words in a seed document at step 103 as shown in FIG. 1.

Those skilled in the art may directly use a given entity word-topic wordpair to filter any candidate document set regardless of the source ofthe any document set. The flow chart as shown in FIG. 7 may also be likeFIG. 7A: Step 701A—giving an entity word-topic word pair; step702A—giving a candidate document set; and step 703A—filtering thecandidate document set with the entity words and topic words in thegiven entity word-topic word pair to generate a filtered document set.FIG. 7A is related to FIG. 7 in: the given entity word-topic word atstep 701A may come from the entity word-topic word pair formed at step704 of FIG. 7, and the candidate document given at step 702A may be theseed document at step 701 of FIG. 7. All entities in all the entityword-topic word pairs received at step 701A may form an entity word set,while for each entity word in the entity word set, all topic wordscorresponding to the entity word form a topic entity set correspondingto the entity word, and the “corresponding” here refers to acorrespondence relationship embodied through a entity word-topic wordpair.

FIG. 8 shows a flow chart of a method of filtering an expanded documentset according to an embodiment of the present invention. For eachexpanded document in the expanded document set, steps 801-806 areexecuted. In other words, filtering the whole expanded document set isimplemented by filtering each expanded document. First, the entity wordsin the expanded document are identified at step 801, and then the topicwords of the expanded documents related to the based entity words areidentified at step 802 based on the identified entity words. The mannerof identifying entity words and topic words of the expanded documents inthe expanded document set at steps 801 and 802 is identical to themanner of identifying entity words and topic words of a seed document ina seed document set. For details, refer to FIG. 2, FIG. 3 and thecorresponding literal descriptions, which will not be detailed here.

After the entity words and topic words of the expanded document areidentified, at step 803, the entity words identified in the expandeddocument are compared with the entity words in the entity word set ofthe seed document set to determine whether there exist a entity word inthe entity word set in the seed document set which is same as the entitywords identified in the expanded document at step 801, and if existed,the process proceeds to a determining step 804; if none of the entitywords in the entity word set in the seed document set is same as to theentity words of the identified expanded document at step 801, then atstep 806, it is determined that the documents in the expanded documentset are required to remove “noises” therefrom, thereby not adding thedocuments into a filtered document set. The so-called entity word set ina seed document set refers to a set of all identified entity words afterperforming operation to each seed document in the seed document set atsteps 101-104 as shown in FIG. 1.

It should be noted that there is no absolute execution sequence for step802 and step 803. The determining of step 803 may be performed after theentity words and topic words of the expanded document are identifiedfirst, or the determining of step 803 is directly performed after theentity words of the expanded document are identified, and then after thedetermining ends, the step 802 is further performed to identify out thetopic words if necessary.

At step 804, it is determined whether the topic word in the expendeddocument identified based on the entity word is identical to a topicword identified based on a same entity word in the entity word set ofthe seed document set. If there is such topic word in the seed documentset, the process proceeds to step 805 to add the expanded document intothe filtered document set; and otherwise, the process proceeds to step806 to determine that the expanded document is required to filter out“noises” therefrom, thereby not adding the expanded document into thefiltered document set. To sum up, by the method of filtering an expandeddocument set as shown in FIG. 8, the objective of removing “noisy”expanded documents in the expanded document set can be achieved, therebyimproving the precision of expanding the seed document set.

Apparently, in an enterprise search service scenario, a seed documentset and a filtered document set are both document sets in an enterprisesearch service data source, available for search by enterprise searchusers, while the expanded document set, due to presence of “noise”, isnot a document set in an enterprise search service data source. In thecase where it is unnecessary to filter out the noises in the expandeddocument set, that is, the requirement on the precision of expandingdocuments is not high, since there is no filtered document set, the seeddocument set and the expanded document set are document sets in theenterprise search service data source.

Though FIG. 8 shows detailed steps of filtering an expanded document setgenerated at step 104 as shown in FIG. 1, it is apparent that the stepsas shown in FIG. 8 are likewise applicable to the process of filtering acandidate document set in the case of the given entity word-topic wordpair as shown in FIG. 7A, as long as the “expanded document” inrespective step of FIG. 8 is replaced with “candidate document”, and the“entity word set in a seed document set” is replaced with the “entityword set of a given entity word-topic word pair.” For details, refer toFIG. 8A.

FIG. 9 shows a structural diagram of a document processing systemaccording to the present invention. The system is generally indicated by900 in FIG. 9. Specifically, the system as shown in FIG. 9 is configuredto perform the following operations on each seed document in a seeddocument set to thereby generate an expanded document set. The system900 comprises entity word identifying means 901, topic word identifyingmeans 902, pairing means 903, and document expanding means 904. Theentity word identifying means 901 identifies entity words in a seeddocument. The topic word identifying means 902 is coupled to the entityword identifying means 901 and is configured to identify topic words ofthe seed document based on the identified entity words. The paring means903 pairs the entity words identified by the entity word identifyingmeans 901 and the topic words identified by the topic word identifyingmeans 902 based on the entity words into entity word-topic word pairs.

The document expanding means 904 searches and downloads new documentsthrough the network by taking the entity word and topic word in theentity word-topic word pair paired by the pairing means 903 as key wordsat the same time, thereby forming an expanded document set formed fromthe expanded documents. It should be pointed out that, means 901-904 inthe system as shown in FIG. 9 correspond to steps 101-104 in the methodas shown in FIG. 1, respectively, and thus their respective specificimplementation process will not be detailed here. Those skilled in theart may appreciate that the seed document set may be automaticallyexpanded with the system as shown in FIG. 9, so as to form an expandeddocument set. Under the environment of enterprise search service, thecontent of a search data source is automatically expanded from theoriginal seed document set to a sum of the seed document set and theexpanded document set.

FIG. 10 shows a structural diagram of a document processing systemaccording to a preferred embodiment of the present invention. The systemis generally indicated by 1000 in FIG. 10. Specifically, the system asshown in FIG. 10 comprises document receiving means 1001, entity wordidentifying means 1002, topic word identifying means 1003, pairing means1004, document expanding means 1005, and document filtering means 1006.Different from the system as shown in FIG. 9, the system of FIG. 10 addsthe document receiving means 1001 and the document filtering means 1006.

The document receiving means 1001 receives recommended documents to forma seed document set, and the document filtering means 1006 filters thedocuments in the expanded document set obtained from the documentexpanding means 1005 to form a filtered document set, thereby removingthe “noises” in the expanded document set and improving precision ofexpanding the seed document set. It should be pointed out that means1001-1006 of the system of FIG. 10 correspond to steps 701-706 of themethod as shown in FIG. 7, respectively, while the document filter means1006 may be further configured to implement steps 801-806 in the methodas shown in FIG. 8.

FIG. 11 shows a structural diagram of a document processing systemaccording to the document processing methods as shown in FIG. 7A andFIG. 8A; The system as shown in FIG. 11 is generally indicated by 1100,and specifically the system 1100 comprises receiving means 1101, entityword identifying means 1102, topic word identifying means 1102, anddetermining means 1104. The receiving means 1101 corresponds to the step701A as shown in FIG. 7A, for receiving a given entity word-topic wordpair. The entity word identifying means 1102 corresponds to the step801A as shown in FIG. 8A, for identifying the entity words of eachcandidate document in a given candidate document set. The topicidentifying means 1103 corresponds to the step 802A as shown in FIG. 8A,for identifying, based on the identified entity word, the topic words ofthe candidate document related to the based entity words. Thedetermining means 1104 corresponds to steps 803A-805A as shown in FIG.8A, for determining whether to add the candidate document into thefiltered document set.

FIG. 12 shows a structural diagram of an implementation of an enterprisesearch service system according to a method of the present invention.Hereinafter, each arrow marked in FIG. 12 will be explained in detail.Arrow 1 indicates that users of an enterprise search service obtain adocument in their interest through web information and service, but notthrough the enterprise search service system per se. The connectionbetween web information and service and enterprise search service usersas shown in FIG. 12 may use a routine network connection such as tokenring, Ethernet, WiFi, or other routine communication standard. Besides,the network may comprise any kind of network including Internet, widearea network (WAN), local area network (LAN), and virtual privatenetwork (VPN).

If a client communicates with a server via Internet, the connection canbe provided based on the traditional TCP/IP socket-based protocol andthe client would establish a connection with the server through anInternet service provider. Arrows 2 and 3 indicate that users of theenterprise search service recommend the valuable documents which theyobtain through the web information and service to an information memorydevice of the enterprise search service system via an informationrecommendation module. The information memory device is a memory devicefor storing the search data source of the enterprise search service.

Arrow 4 indicates that an information intelligent expansion modulereceives the documents recommended by users stored in the informationmemory device to perform expanding operation to these documents. Theinformation intelligent expansion module comprises a natural languageprocessing module for performing FNER entity word recognition and FTDtopic word detection. Arrow 5 indicates that the information intelligentexpansion module, after the identified entity words and topic words formpairs, sends them to an information timed download module which submitssearch and download requests to the web information and serviceaccording to a predetermined time interval as shown in arrow 6, anddownloads the expanded new documents.

Arrow 7 indicates that the information timed download module sends thedownloaded new documents to the information intelligent expansion modulewhich filters these new documents to remove the “noises” therein, andthen the information intelligent expansion module sends the remained newfiltered documents to the information memory device, while these newdocuments and the previously user recommended documents together becomethe search data source of the enterprise search service.

Filtering is shown in FIG. 9, where enterprise search service users maysearch the desired documents from the expanded search data source storedin the information memory device via the information search module. Itcan be seen from the system of FIG. 11 that by introducing theinformation intelligent expansion module and the information timeddownload module, not only new documents can be automatically downloadedfrom the web as timed to thereby implement document expansion, but alsothe downloaded new documents can be filtered to thereby guarantee theprecision and accuracy of document expansion, which will not excessivelyconsume the memory resources of the information memory device of theenterprise search service system.

Although the above description on the preferred embodiments, thoseskilled in the art should appreciate that the above system, device andmethod may be implemented by using a computer executable instructionand/or by being included in a processor control code. For example, suchcode is provided on a magnetic diskette, carrier medium of CD orDVD-ROM, a programmable memory such as read-only memory (firmware) ordata carrier such as an optical or electronic signal carrier. Thedevice, the server and units thereof according to the presentembodiments may be implemented by a Super-Large Scale Integration or agate array, a semiconductor such as logic chip and transistor, orhardware circuitry of a programmable hardware device such asfield-programmable gate array or a programmable logic device and mayalso be implemented by combination of the above hardware circuitry andsoftware.

Although the system and method of the present invention of utilizingremote application to process local document have been described indetail with reference to the preferred embodiments, the presentinvention is not limited hereto. Those skilled in the art can makevarious alterations, replacements and modifications to the presentinvention without departing from the spirit and scope of the presentinvention under the teaching of the present description. It should beunderstood that all such alternations, replacements and modificationsstill fall within the scope of protection of the present invention.

1. A method for expanding a seed document in a seed document set,wherein the seed document set comprises at least one seed document, themethod comprising: identifying one or more entity words of the seeddocument in memory by a processor, wherein the one or more identifiedentity words are words indicating focused entities of the seed documentand the one or more identified entity words of the seed document areidentified with focused named entity recognition (FNER) technology, theFNER technology comprising: segmenting the seed document; applying partof speech tagging; identifying candidate entity words; extractingfeature values for each candidate entity word to form a feature vector;setting a threshold and setting a weight for each feature value in thefeature vector; calculating a score of each candidate entity word withthe feature vector and the weight; and comparing the score with the setthreshold and determining entity words from the candidate entity wordsas the one or more identified entity words; identifying by theprocessor, based on each of the one or more identified entity words ofthe seed document, one or more topic words related to each of the one ormore identified entity words, the one or more identified topic wordslocated in the seed document, wherein the one or more identified topicwords of the seed document are identified with focused topic detection(FTD) technology using the segmenting of the seed document and the partof speech tagging of the FNER technology as a basis for identifying theone or more topic words; forming, by the processor, an entity word-topicword pair from each of the one or more identified topic words and eachof the one or more identified entity words upon which each of the one ormore identified topic words is identified; and obtaining one or moreexpanded documents by the processor by taking the entity word and topicword in each entity word-topic word pair as key words for web searchingat the same time, wherein the expanded documents comprise not only theentity word in the each entity word-topic word pair but also the topicword in the each entity word-topic word pair.
 2. The method according toclaim 1, wherein the identifying by the processor, based on the each ofthe one or more identified entity words of the seed document, one ormore topic words related to each of the one or more identified entitywords further comprises: identifying the one or more topic words basedon a distance between words other than the one or more identified entitywords in the seed document.
 3. The method according to claim 1, whereinthe identifying by the processor, based on the each of the one or moreidentified entity words of the seed document, one or more topic wordsrelated to each of the one or more identified entity words furthercomprises: identifying the one or more topic words based on a frequencyof other words than the one or more identified entity words in the seeddocument and the one or more identified entity words upon which each ofthe one or more identified topic words is identified appearing in a samesentence in the seed document.
 4. The method according to claim 1,further comprising receiving a recommended seed document to form theseed document set.
 5. A system for expanding a seed document in a seeddocument set, wherein the seed document set comprises at least one seeddocument, the system comprising: entity word identifying means foridentifying one or more entity words of the seed document in memory by aprocessor, the one or more identified entity words being wordsindicating focused entities of the seed document, wherein the entityword identifying means includes focused named entity recognition (FNER)technology, the FNER technology comprising: segmenting the seeddocument; applying part of speech tagging; identifying candidate entitywords; extracting feature values for each candidate entity word to forma feature vector; setting a threshold and setting a weight for eachfeature value in the feature vector; calculating a score of eachcandidate entity word with the feature vector and the weight; andcomparing the score with the set threshold and determining entity wordsfrom the candidate entity words as the one or more identified entitywords; topic word identifying means for identifying by the processor,based on each of the one or more identified entity words of the seeddocument, one or more topic words related to each of the one or moreidentified entity words, the one or more identified topic words locatedin the seed document, wherein the topic word identifying means isconfigured to identify the one or more topic words of the seed documentwith focused topic detection (FTD) technology using the segmenting ofthe seed document and the part of speech tagging of the FNER technologyas a basis for identifying the one or more topic words; pairing meansfor forming, by the processor, an entity word-topic word pair from eachof the one or more identified topic words and each of the one or moreidentified entity words upon which each of the one or more identifiedtopic words is identified; and document expanding means for obtainingone or more expanded documents by the processor by taking the entityword and topic word in the each entity word-topic word pair as key wordsfor web searching at the same time, the expanded documents comprisingnot only the entity word in each entity word-topic word pair but alsothe topic word in the each entity word-topic word pair.